The present invention relates to a cartridge suitable as a disk cartridge for housing or exchangeably housing a recording medium such as an optical disk or a magneto-optical disk, for example, an MO or DVD-RAM. In particular, the present invention pertains to the technical field of a dustproof structure for preventing permeation of dust in a cartridge of a type including a shutter for opening/closing an opening portion through which an insertion member such as a pickup or a disk table is to be inserted in the cartridge.
FIG. 60 shows a related art disk cartridge 101 such as an MO, DVD, or DV-ROM. The disk cartridge 101 includes an upper shell 102 and a lower shell 103 between which a disk D such as an optical disk or a magneto-optical disk is to be rotatably housed. A slot-shaped opening portion 104 for insertion of a pickup and a disk table therethrough is formed along the lower shell 103 or along a central portion between the upper and lower shells 102 and 103. A shutter 105 formed into a nearly L-shape or U-shape for opening/closing the opening portion 104 is mounted to the outside of the lower shell 103 or the outside of the upper and lower shells 102 and 103. In operation, the shutter 105 is slid in the directions “u” and “v” along one side surface 101a of the disk cartridge 101, to open/close the opening portion 104.
With respect to a dustproof mechanism, however, the above-described related art disk cartridge 101 is only configured as follows: namely, as shown in FIG. 61, in a shutter closed state that the shutter 105 closes the opening portion 104 in the direction “v”, both ends 105a of the shutter 105 in the directions “u” and “v” are overlapped to both side edges of the opening portion 104 of the disk cartridge 101 by distances OL1. It is to be noted that in the figure, character S1 denotes a movement stroke (or opening/closing stroke) of the shutter 105.
Accordingly, in such a shutter closed state, air AR containing dust DT is easy to permeate in the disk cartridge 101 through the opening portion 104 via small gaps 106 between both the ends 105a of the shutter 105 and both the side edges of the opening portion 104 of the disk cartridge 101, with a result that the dust DT is liable to adhere on the surface of the disk D. The adhesion of the dust DT on the surface of the disk D tends to cause errors at the time of recording and/or reproducing operation of data, and such errors are difficult to be corrected. In this way, the permeation of the dust DT causes a problem in the high density recording disk cartridge.
To solve the above problem, it may be considered to provide a dustproof structure shown in FIG. 62. As shown in the figure, a pair of parallel inner ribs 107 are formed on both the ends 105a of the shutter 105 in the directions “u” and “v” as the slide directions in such a manner as to project downwardly therefrom, and a pair of parallel outer ribs 108 are formed on portions, outside of both the side edges, of the opening portion 104 of the disk cartridge 101 in such a manner as to project upwardly therefrom, to thereby form gaps 106 bent into nearly L-shapes at both the side edges of the opening portion 104. Such a dustproof structure is effective to reduce the permeation of the air AR containing the dust DT in the disk cartridge 101 to some extent.
The above-described dustproof structure, however, has a disadvantage. The gaps 106 between both the ends of the shutter 105 and both the side edges of the opening portion 104 of the disk cartridge 101 cannot be made zero because the shutter 105 must be slid in the directions “u” and “v” relative to the disk cartridge 101. As a result, the dust DT composed of particles in the order of μm is liable to permeate in the disk cartridge 101 through the gaps 106.
Alternatively, it may be considered to provide a dustproof structure shown in FIG. 63, which structure is modified from that shown in FIG. 62. As shown in the figure, overlapped amounts OL2 between both the ends 105a of the shutter 105 and both the side edges of the opening portion 104 of the disk cartridge 101 are made sufficiently longer, to increase the flow resistance of the air AR containing the dust DT permeating from the pair of gaps 106, thereby suppressing the permeation of the air AR.
The above-described dustproof structure, however, has problems that since the movement stroke (or opening/closing stroke) S2 of the shutter 105 becomes large, such a structure is unstable for the small-sized disk cartridge 101, and that it is difficult to prevent permeation of the dust DT composed of particles in the order of μm for the same reason as that described with reference to FIG. 62.